WASHINGTON — A federal court is putting on hold a controversial Obama administration regulation aimed at reducing power plant pollution in 27 states that contributes to unhealthy air downwind.

More than a dozen electric power companies, municipal power plant operators and states had sought to delay the rules until the litigation plays out. A federal appeals court in Washington approved their request Friday.

Republicans in Congress have attempted to block the rule using legislation, saying it would shutter some plants and kill jobs. While those efforts succeeded in the Republican-controlled House, the Senate in November rejected an attempt to stay the regulation.

The rule, finalized by the Environmental Protection Agency in July, replaces a 2005 Bush administration proposal that was rejected by a federal court.

The Bush-era rule will remain in effect.